Migrants from countries like Eritrea, Cameroon, and Mexico have flooded the U.S. southern border in San Diego to such an extent in recent days that U.S. border officials have been unable to process them without long lines forming on the Tijuana side of the border.

Nearly 100 migrants lined up in a plaza on the Mexico side of the border that leads to the San Ysidro pedestrian border crossing in San Diego last week because of the backlog, according to the San Diego Union Tribune. Mexican officials told those who tried to sleep in the plaza that they had to leave. Eritrean migrants cited in the article claimed that last Monday 25 migrants were temporarily jailed for waiting in the plaza.

One of the Eritrean migrants told the Tribune that he felt racism, “big discrimination,” and no respect in Mexico.

U.S. Customs and Border Protection (CBP) officials are working to process the foreign nationals that arrive at the border and are working with U.S. Immigration and Customs Enforcement (ICE), according to one who spoke with the Tribune. It takes time to process each individual and move them from holding cells to detention.

As the report details, migrants who claim fear of returning to their country are transferred to other immigration officials for consideration of potential asylum cases. An excess of these cases can back up the space available to process more individuals.